The invention relates to a throttle valve body for an internal combustion engine, comprising a housing and a crossflow opening in the housing, which can be blocked by a throttle valve, the throttle valve being arranged on a throttle valve shaft which can be driven so as to pivot about its longitudinal axis extending transversely with respect to the longitudinal axis of the crossflow opening and whose free ends are mounted such that they can pivot in bearings which are arranged in bearing recesses in the housing, and the throttle valve shaft being secured against axial displacement by an axial safety device, in its regions in which the throttle valve shaft protrudes axially, the throttle valve having run-on surfaces which bear on supporting regions fixed to the housing.
In such throttle valve bodies, in order to secure the throttle valve shaft axially, it is known to arrange a radially circumferential groove in their regions projecting into the bearing recess, into which groove a retaining element fixed to the housing projects radially.
If the groove is machined into the throttle valve shaft, this weakens the stability of the throttle valve shaft. Rings pressed onto the throttle valve shaft, between which the groove is formed, need accurate and therefore expensive fits and entail the risk of shaft deformation and therefore impairment of the shaft circularity. This leads to increased friction and therefore to a poorer torque balance requiring more powerful return springs for returning the throttle valve into the idling position, and more powerful and therefore larger motors for adjusting the throttle valve shaft.
The construction of the axial safety device is complicated, needs a great deal of space and can be mounted only laboriously. Furthermore, in the case of such axial safety devices, high production accuracies have to be maintained in order that the throttle valve can be positioned accurately in the crossflow opening.
U.S. Pat. No. 5,275,375 discloses a throttle valve body of the type mentioned at the beginning in which the supporting regions are formed by those regions of the inner wall of the crossflow opening of the housing which surround the bearing recesses. Therefore, the position of the throttle valve in the crossflow opening depends on the production tolerances of throttle valve and crossflow opening.